The present invention relates to an optical information recording apparatus and method, and an optical information recording medium. For example, the present invention is applicable to a recording apparatus for a compact disk (CD) and a digital video disk (DVD), and to its recording method. According to the present invention, a positional information of laser beam irradiation position on a polar coordinate is converted into a positional information on a rectangular coordinate so as to access the corresponding image data, and then, in accordance with the image data, a laser beam power is controlled. Whereby it is possible to readily and visibly record characters and images in an information recording surface of a CD or the like.
Moreover, according to the method determined based on the CD and DVD standards, a recording laser is turned on and off, and thereby, information such as music and a video signal is recorded on an optical disk. Simultaneously, the recording laser output (power) is gently varied, and thereby, it is possible to record a second information which is not determined in the CD and DVD standards, in the identical optical disk.
In the present invention, according to the method determined based on the CD and DVD standards, a recording laser is turned on and off, and thereby, information such as music and a video signal is recorded on an optical disk. Simultaneously, a luminous pulse of the recording laser is divided into two parts, or is made so as to have a depressed portion, and thereby, it is possible to record a second information which is not determined in the CD and DVD standards, in the identical optical disk.
Further, the optical information recording medium of the present invention can record a new information such as a watermark capable of being visibly confirmed by seeing a disk, a visible image or the like, in addition to the above information such as music and a video signal determined based on the CD and DVD standards.
Conventionally, in this type of optical information recording medium, for example, a compact disk, a data used for recording is subjected to data processing, and thereafter, is modulated according to an EFM (Eight to Fourteen Modulation)(hereinafter, referred simply to as xe2x80x9cEFM-modulatedxe2x80x9d). In this manner, a pit line is formed in the compact disk, and has a period 3T to 11T with respect to a predetermined basic period T, and thereby, an audio data or the like is recorded.
On the contrary, in a compact disk player, a laser beam is irradiated to a compact disk, and then, a return light is received, and thereby, it is possible to obtain a regenerative signal of the return light, which has a signal level which varies in accordance with a light quantity. Then, the regenerative signal is binarized according to a predetermined slice level so that a binary signal is generated. Further, according to the binary signal, a PLL circuit is driven so as to generate a reproducing clock, and the binary signal is successively latched by the reproducing clock, and thereby, it is possible to generate a reproductive data having a period 3T to 11T corresponding to a pit line formed in the compact disk.
The compact disk player decodes the reproductive data thus generated according to the data processing corresponding to data processing in recording, and then, a pit line is formed on a compact disk substrate. Further, a reflection film is formed on the disk substrate, and thus, an information recording surface is formed thereon. Moreover, characters such as a title, a name of music and a maker name, and images are visibly printed on the information recording surface according to screen process printing.
For example, according to Japanese Patent Application No. 8-205292 as filed on Jul. 16, 1996 by the applicant, the following optical disk apparatus has been disclosed therein. More specifically, in accordance with all signal pattern to be recorded, a displacement shifted from an ideal edge position of the regenerative signal is determined, and then, a table is prepared. Further, with the use of the table, an edge position of a recording signal is varied and recorded in accordance with a recording signal pattern, and thereby, a jitter can be removed. Thus, it is possible to overlap and record characters and figures, that is, a second information which is not included in the CD standards, in a signal recording area of the compact disk (CD). Further, according to Japanese Patent Application No. 9-67843 as filed on Mar. 5, 1997 by the applicant, the an following optical disk apparatus has been disclosed therein. More specifically, an ID pattern such as a bar code by a watermark is recorded in a read-in or signal recording area of an optical disk, and then, the pattern is electrically detected. By doing so, a disk ID or cipher is read out so as to prevent a copy or pirated edition of the optical disk from appearing on the market. Further, according to Japanese Patent Application No. 9-298328 as filed on Oct. 30, 1997 by the applicant, the following optical disk apparatus has been disclosed therein. More specifically, in order to show a cutting position, the optical disk apparatus includes a circuit which converts a polar coordinate of a radius (track number) and a rotational speed (number of FG pulse) into a rectangular coordinate at a real time, and thereby, a data expressed by the rectangular coordinate system is used as it is, and then, it is possible to carry out cutting. Of course, these optical disk apparatuses record an EFM-modulated signal which is determined in the compact disk standards, in addition to information such as characters, figures or the like. Therefore, it is possible to reproduce an optical compact disk by the conventional player, and in addition, characters and figures are recorded in the signal area of the disk, so that a disk having a high value added can be manufactured.
Moreover, Japanese Patent application No. 9-347532 filed by the present applicant have disclosed an optical information recording apparatus, an optical information recording method and an optical information recording medium, which can record second information such as characters and figures recorded on a disk as a difference of laser output power, and as a result, can record a clear second information. In addition, Japanese Patent application No. 9-173811 filed by the present applicant have disclosed an optical disk recording apparatus, an optical disk and an optical disk reproducing apparatus (player), which divides a pit having a period 9T or more into 4T+1T+4T so that a space is recorded as the center 1T in place of a pit, and thereby, can record a new information depending upon the pit whether or not it is divided into two.
According to the invention disclosed in the aforesaid Patent Applications, there is the possibility that a signal characteristic is variable in boundary portion where a laser output varies; for this reason, a change of the laser output is not too widely taken. As a result, there is a problem that the recorded second information such as characters and figures are not clear. Moreover, in production and sale of the optical disk such as CD and DVD, a illegal copy and an expansive sale of disk are an important matter. One method for preventing the illegal copy is to record a watermark (pattern) on the disk similarly to that carried out in bills (paper money). The recorded watermark is a visible or dim image, or an invisible signature which is visibly stood out on an information layer of the disk detected by a special hardware. The disk having the watermark is not transferred even in the case of being copied by a conventional technique; therefore, it is possible to simply confirm a truth of the disk.
Unexamined Patent Publication (Kokai) No. 10-31825 has disclosed a method of recording a watermark (pattern) on an optical disk by varying a size of an information pit. In two areas on the disk having an information pit of different size, a contrast of reflection light is visible to a user (observer). In order to manufacture the disk as described above, a laser beam intensity (power) in a mastering process is modulated in accordance with a pattern to be recorded.
When reading out the disk, a regenerative signal generated as the result is affected by a size of the modulated pit. In order to reproduce the disk with the use of the conventional reproducer (player), a pit edge position is corrected so as to shape the regenerative signal for correctly reproducing the disk by the reproducer. Further, in order to securely and safely reproduce the disk, a change from a certain power level to other power level is carried out by slowly varying an optical modulation input voltage of a mastering machine, in place of suddenly changing a voltage.
In order to achieve a desired smooth change, the modulation voltage changing function must be carefully selected on the basis of the following three problems.
First, an optical modulator for modulating a light intensity has a non-linear characteristic to be considered. Secondary, a optical intensity level of the optical modulator and a shift of an information pit edge are interacted, and must be properly selected. Thirdly, the characteristic of the optical modulator depends upon an alignment of a mastering machine, and is variable according thereto.
The following is a description on the most simple method for solving the above problems. In the case of transferring the light intensity from a certain light intensity to other light intensity, a voltage of the optical modulator is gradually variable at an equal voltage step. Simultaneously, in each modulation voltage, a pit edge position is gradually moved bit by bit according to an linearly interpolated value. According to this method, the optical modulator is operated well unless it has non-linear characteristic. However, when a cutting operation is carried out by using a simple interpolation, in the case of using an optical modulator having a non-linear characteristic, in a regenerative signal RF of the manufactured optical disk, an overshoot is generated in envelop; as a result, a jitter is worsen.
The proper method for recording the conventional watermark pattern is realized by collectively changing a light intensity level of a recording laser during disk mastering. However, according to this conventional method, if the recording jaw power is collectively changed during mastering, an non-alignment portion is generated in the vicinity of a change point in a waveform of the regenerative signal, and there is a problem that depending upon a player, an error rate is worsen in the vicinity of the change point.
Further, the above Unexamined Patent Publication (Kokai) No. 10-31825 has disclosed a method of correcting a waveform (figure) of the regenerative signal by replacing a pit edge depending upon a recording power level. This shows that according to a change of signal characteristic, in a change of the watermark pattern allowable in the player, a laser power is slowly changed. However, there is a problem that the nonlinearity of the optical modulator must be specially considered.
Unexamined Patent Publication (Kokai) No. 7-201079 has disclosed a technique of forming a reflection layer on a surface of a card main body using a phase-change area such as a phase-change layer as a visibly or invisibly information such as characters, pictures and patterns. However, the above Unexamined Patent Publication (Kokai) No. 7-201079 has no any consideration relative to the aforesaid problems.
It is, therefore, an object of the present invention to provide an optical information recording medium, an optical information recording apparatus and an optical information recording method, which can clearly record a second information such as recorded characters and figures in an information recording surface of a compact disk.
In order to solve the above problems, according to the present invention, in the optical information recording In apparatus and method, a positional information by a polar coordinate based on a rotation of the optical information recording medium is converted into a positional information by a rectangular coordinate, and then, the positional information by the rectangular coordinate is addressed so as to output an image data, and thus, in accordance with the image data, a laser beam power is varied.
The laser beam power is varied in accordance with the positional information by the polar coordinate so as to vary a pit width, and thereby, it is possible to change a reflection factor of the information recording surface in synchronous with a rotation of the optical information recording medium, and thus, to visibly record characters and images. At this time, the positional information by the polar coordinate is converted into the positional information by the rectangular coordinate so as to access the image data, and thereby, the rectangular coordinate used in various information apparatuses is addressed, and for example, a binary image data is used as it is, and thus, characters and figures can be recorded. Therefore, it is possible to readily record a visible character and image.
Further, according to the present invention, it is possible to record a second information such as characters and figures recorded on a disk with the use of a difference of laser output power; as a result, a clear second information can be recorded. In addition, in the optical information recording medium of the present invention, it is possible to make large a change of the pit width by the second information, so that the second information can be more clearly confirmed.
Further, according to the present invention, a modulation signal, which is variable in accordance with the first information, is generated, and a time changing signal, which is variable according to the second information with a time, is generated. Then, a laser power is varied according to the time changing signal, and a laser beam obtained from the change of output power is on/off-controlled according to the modulation signal, and thereby, a change of the laser power by the second information is gently carried out. Moreover, the first information is recorded by mainly varying a pit length and position; on the other hand, the second information is recorded by mainly varying a pit width. Whereby a change of the pit width by the second information is stepwise carried out.
Further, according to the present invention, in accordance with the first information, a signal level is changed over at a period of integer multiples of a predetermined basic period, and thereby, a first modulation signal is generated, and then, a relative positional information on a disk-like recording medium is detected by means of a pickup. In accordance with the relative positional information, the second information is generated, and then, according to the second information, a part of the modulation signal is modified, and thus, the laser beam is modulated according to an output of the second modulation means.
The first information is recorded by mainly changing the pit length and position, and the second information is recorded in a manner that of the pits, a pit having a predetermined length or more is divided into two parts or if formed so as to have a depression or bulge, and thus, the second information forms a two-dimensional pattern on the optical information recording medium.
Further, according to the present invention, when slicing into a binary in reproducing, a time of the recording signal is previously corrected so that no jitter is generated.
Further, according to the present invention, a transition area of a pit change based on the second information ranges from 0.1 mm to 1 mm; therefore, a pattern is not dim, and the second information can be clearly confirmed.
Further, according to the present invention, a laser intensity of the modulated laser beam is measured, and a driving signal of the modulated laser beam is controlled, and further, an intensity characteristic of the laser beam is measured with respect to a predetermined pair of amplitudes of the driving signal. In this manner, an invert operation of the above characteristic is carried out so as to store an invert operation value which is a driving signal corresponding to a certain power intensity.
Then, a timing correction value relative to an intermediate power intensity level is determined in a displacement period for linearly interpolating a timing value at a predetermined power intensity level, and thereby, in an invert operation for storing the invert operation characteristic for outputting a desired power intensity, the laser power intensity is directly controlled during a change period for investigating a necessary driving amplitude. As a result, the regenerative signal of the optical information recording medium has a smooth change in a range where a recording power intensity varies, and thereby, the optical information recording medium can be stably reproduced.